UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


THE  UTILIZATION  OF  THE   NITROGEN 

AND  ORGANIC  MATTER  IN  SEPTIC 

AND  IMHOFF  TANK  SLUDGES 


BY 
C.  B.  LIPMAN  and  P.  S.  BURGESS 


BULLETIN  No.  251 

Berkeley,  Cal.,  April,  1915 


UNIVERSITY  OF  CALIFORNIA  PRESS 
BERKELEY 
1915 


Benjamin  Ide  Wheeler,  President  of  the  University. 
EXPERIMENT  STATION  STAFF 

HEADS   OF  DIVISIONS 

Thomas  Forsyth  Hunt,  Director. 

Eugene  W.  Hilgard,  Agricultural  Chemistry  (Emeritus). 

Edward  J.  Wickson,  Horticulture. 

Herbert  J.  Webber,  Director  Citrus  Experiment  Station;  Plant  Breedin; 

Hubert  E.  Van  Norman,  Vice-Director;  Dairy  Management. 

William  A.  Setchell,  Botany. 

Myer  E.  Jaffa,  Nutrition. 

Robert  H.  Loughridge,  Soil  Chemistry  and  Physics  (Emeritus). 

Charles  W.  Woodworth,  Entomology. 

Ralph  E.  Smith,  Plant  Pathology. 

J.  Eliot  Coit,  Citriculture. 

John  W.  Gilmore,  Agronomy. 

Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 

Frederic  T.  Bioletti,  Viticulture  and  Enology. 

Warren  T.  Clarke,  Agricultural. Extension. 

John  S.  Burd,  Agricultural  Chemistry. 

Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 

Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 

Ernest  B.  Babcock,  Genetics. 

Gordon  H.  True,  Animal  Husbandry. 

James  T.  Barrett,  Plant  Pathology. 

Fritz  W.  Woll,  Animal  Nutrition. 

A.  V.  Stubenrauch,  Pomology. 

Walter  Mulford,  Forestry. 

W.  P.  Kelley,  Agricultural  Chemistry. 

William  G.  Hummel,  Agricultural  Education. 

Leon  M.  Davis,  Dairy  Industry. 

John  E.  Dougherty,  Poultry  Husbandry. 

Frank  Adams,  Irrigation  Practice. 

David  N.  Morgan,  Assistant  to  the  Director. 

Mrs.  D.  L.  Bunnell,  Librarian. 

DIVISION   OF    SOIL   CHEMISTRY   AND    BACTERIOLOGY 

Charles  B.  Lipman  Paul  S.  Burgess 

Leslie  T.  Sharp  W.  F.  Gericke 

L.  E.  Bailey 


THE  UTILIZATION  OF  THE  NITROGEN  AND 

ORGANIC  MATTER  IN  SEPTIC  AND 

IMHOFF  TANK  SLUDGES 


BY 

C.  B.  LIPMAN  and  P.  S.  BURGESS 


Through  the  courtesy  of  Professor  Charles  Gilman  Hyde,  Professor 
of  Sanitary  Engineering  at  the  University  of  California  and  Consult- 
ing Engineer  of  the  California  State  Board  of  Health,  the  writers 
are  enabled  to  give  the  following  brief  summary  of  the  sewage  and 
sludge  output  in  California.  There  were  in  the  state  in  October,  1913, 
157  public  sewerage  systems,  serving  a  population  of  about  1,577,100 
and  in  addition  there  were  three  sanitary  districts  with  public  systems 
and  ten  municipalities  with  private  systems.  This  leaves  a  balance 
of  sixty-four  municipalities  with  no  sewerage  systems.  Of  the  com- 
munities which  dispose  of  their  sewage  in  some  manner  only  eighty-nine 
treat  the  sewage  before  final  disposition  thereof.  The  last  mentioned 
number  of  communities  serve  a  population  of  about  284,000,  and  the 
balance  a  population  of  about  1,300,000.  Those  communities  therefore 
which  dispose  of  untreated  sewage  by  dumping  into  fresh  or  salt 
bodies  of  water  make  up  about  78  per  cent  of  the  total  population 
served  by  some  kind  of  sewerage  system,  the  balance  (only  about  22  per 
cent),  treating  the  sewage  in  some  manner  before  finally  disposing  of 
it,  and  even  in  the  latter  cases  practically  none  of  the  treated  sewage 
is  employed  for  agricultural  purposes.  It  must  be  added  here  that  in 
forty-six  cases  representing  a  population  of  195,400,  the  sewage  is 
used  on  sewer  farms  or  on  irrigated  lands. 

On  the  basis  therefore  of  the  figures  above  given,  and  others  it  has 
been  calculated  that  even  if  the  population  whose  sewage  is  employed 
on  sewage  farms  is  omitted  from  the  computation  and  assuming  that 
all  instead  of  only  one  hundred  out  of  two  hundred  and  thirty-four 
communities  were  supplied  with  septic  tanks,  there  should  be  produced 
annually  in  California  about  12,100  tons  of  dry  sludge  merely  from 
a  population  of  1,467,900,  which  is  served  by  sewerage  systems.  Using 
the  conventional  valuations  for  the  so-called  "plant  food"  in  the  air- 

[287] 


288  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

dry  sludge,  the  total  annual  output  above  roughly  estimated  should 
have  a  value  of  $108,100.— Practically  none  of  this  goes  back  to  our 
land  today. 

Naturally  the  suggestion  for  the  use  of  sludges  as  fertilizing  mater- 
ials is  one  of  the  first  ones  made,  but,  such  use  must  be  based  on  some 
adequate  understanding  of  the  agricultural  value  of  the  material  and 
that  depends  not  only  on  the  chemical  composition  of  the  sludge  with 
respect  to  nitrogen,  phosphoric  acid,  and  potash,  but  particularly  with 
respect  to  the  condition  of  ' '  availability ' '  in  which  those  materials  are 
found  therein  and  especially  as  regards  the  nitrogenous  fraction  of 
the  material.  In  order  to  carry  out  the  necessary  determinations  we 
obtained  nine  samples  of  sludge,  the  description  and  partial  composi- 
tion of  which  as  determined  by  us  are  as  given  in  Table  I  which  follows  : 

TABLE  I 

Water 
and  organic 
matter 
No.  Description  Per  cent 

1  Orange  City  Imhoff  tank  49.68 

2  Fullerton  Imhoff  tank  25.31 

3  Anaheim  Municipal  tank  33.09 

4  Lindsay  septic  tank  42.92 

5  Pasadena  Imhoff  tank  29.34 

6  Orange  City  Imhoff  tank  38.41 

7  Worcester,  Mass.,  Imhoff  tank  ....  43.86 

8  Cleveland,  Ohio,  Imhoff  tank  36.37 

9  Chicago,  111.,  Stock  Yards 

Imhoff  tank,  5/14  50.46         49.54         1.73         .400         1.46 


It  will  be  noted  in  Table  I  that  in  no  case  does  the  nitrogen 
content  of  the  different  sludges  exceed  2.66  per  cent  (based  on  the 
air-dry  weight  of  the  material),  and  the  average  nitrogen  content  is 
about  1.84  per  cent.  The  phosphoric  acid  content  of  the  sludges  can 
be  seen  by  reference  to  the  table,  to  be  even  lower  than  their  nitrogen 
content,  and  their  potash  content  does  not  amount  to  over  a  few  hund- 
redths of  one  per  cent  as  indicated  by  an  analysis,  of  the  Orange  City 
sludge  mentioned  in  the  table,  carried  out  by  the  Fertilizer  Control 
laboratory  of  the  University  of  California.  The  commercial  value, 
therefore  of  sludge  material  of  the  kind  under  discussion  could  not  be 
expected  to  exceed  $10  per  ton  of  dry  material  on  the  basis  of  the  con- 
ventional calculations  made  by  fertilizer  chemists. 


Ash 
Per  cent 

Total 

N 

Per  cent 

Nitrate 

N 
Per  cent 

Phos- 
phoric 
Acid 
Per  cent 

50.32 

2.66 

.012 

1.11 

74.69 

1.23 

.045 

.86 

76.91 

1.54 

.115 

.99 

57.08 

1.83 

.090 

.89 

70.76 

1.68 

.135 

1.46 

61.59 

2.38 

.060 

.77 

56.14 

2.10 

.010 

1.82 

63.63 

1.44 

.000 

1.28 

Bulletin  251]   utilization  of  nitrogen  and  organic  matter  289 


AVAILABILITY   OF   THE    NITROGEN   IN   THE   SLUDGE 

Since  nitrogen  is  the  only  important  fertilizer  constituent  in  the 
sludge,  agriculturally  speaking,  and  since  its  quantity  therein  is  not 
great  enough  per  se  to  render  the  sludge  of  great  commercial  value, 
it  next  becomes  important  to  determine  the  degree  of  availability  of 
such  nitrogen.  At  the  present  time  the  only  absolute  method  of 
determining  the  availability  of  nitrogen  in  a  given  fertilizer  for  a  given 
soil  and  crop  is  to  test  it  in  experimental  plots  in  the  field.  Such 
an  empirical  method,  however,  is  lengthy  and  seldom  leads  to  any 
generalized  rule  for  the  use  of  nitrogenous  fertilizers.  On  the  other 
hand,  the  arbitrary  chemical  methods  now  used  to  determine  "avail- 
ability" of  nitrogen  seem  to  have  but  little  relation  to  the  actual  condi- 
tion of  availability  of  nitrogenous  materials,  so  far  as  field  conditions 
are  concerned. 

In  these  experiments,  a  new  method  therefore  has  been  introduced, 
namely,  the  determination  of  the  degree  to  which  the  nitrogen  of  the 
sludge  in  this  case  is  changed  to  nitrates  by  the  nitrifying  bacteria  of 
the  soil.  This  is  undoubtedly  a  change  which  all  nitrogenous  materials 
in  the  soil  undergo  to  some  extent  and  our  tests  therefore  will  only 
differ  in  degree,  but  not  in  kind,  from  those  which  sludge  nitrogen 
will  undergo  under  field  conditions. 

As  a  result  of  these  experiments,  we  have  been  able  to  determine 
in  the  case  of  nine  sludge  samples  obtained  through  the  courtesy  of 
Professor  C.  G.  Hyde,  the  amount  of  nitrogen  which  is  actually  trans- 
formed from  the  organic  form  into  nitrates  in  every  one  of  the  sludges 
as  tested  in  three  different  soil  types,  one  from  Anaheim,  one  from 
Davis  and  one  from  Oakley,  California.  The  sludges  were  also  tested 
in  three  eastern  soils.  The  results  obtained  in  the  three  California  soils 
are  set  forth  in  Tables  II,  III,  and  IV.  The  results  in  the  eastern  soils 
are  not  given  here,  but  are  very  much  the  same  in  nature  as  those  of 
the  California  soils,  with  the  exception  that  a  higher  availability  is 
obtained  for  the  sludges  throughout. 


290 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


TABLE  II 

Availability  of  Nitrogen  in  Sludges  in  Anaheim  Sand   (Cal.) 

Nitrate  N  Mgs.  nitrate 

found  nitrogen  Total 

after  in  N  in 

incubation    f A N  sludge 

No.                   Description                                     mgs.  Soil       Sludge  mgs. 

1  Orange  City  Imhoff  tank  8.00  .65         .12  26.6 

2  Fullerton  Imhoff  tank  6.00  .65         .45  12.3 

3  Anaheim  Municipal  tank  8.00  .65       1.15  15.4 

4  Lindsay  septic  tank  5.00  .65         .90  18.3 

5  Pasadena  Imhoff  tank 8.00  .65       1.35  16.8 

6  Orange  City  Imhoff  tank  6.00  .65         .60  23.8 

7  Worcester,  Mass.,  Imhoff  tank       8.00  .65         .10  21.0 

8  Cleveland,  Ohio,  Imhoff  tank       7.00  -.65         .00  14.4 

9  Chicago,  111.,  Stock  Yards 

Imhoff  tank,  5/14  6.40  .65       4.00  17.3         1.75 


Nin 
sludge 
nitri- 
fied 
mgs. 
7.25 

Per  cent 
N  in 
sludge 
nitri- 
fied 
27.2 

5.00 

40.6 

6.20 

40.2 

3.45 

18.8 

6.00 

35.7 

4.75 

15.7 

7.25 

34.5 

6.35 

44.1 

10.1 


TABLE  III 

Availability  of  Nitrogen  in  Sludges  in  Davis  Clay  Loam  (Cal.) 

Nitrate  N  Mgs.  nitrate 

found  nitrogen  Total 

after  in  N  in 

incubation  r A >»  sludge 

No.  Description  mgs.  Soil       Sludge  mgs. 

1  Orange  City  Imhoff  tank  9.00  .25         .12  26.6 

2  Fullerton  Imhoff  tank  6.00  .25         .45  12.3 

3  Anaheim  Municipal  tank  6.40  .25       1.15  15.4 

4  Lindsay  septic  tank  6.40  .25         .90  18.3 

5  Pasadena  Imhoff  tank  8.00  .25       1.35  16.8 

6  Orange  City  Imhoff  tank  7.00  .25         .60  23.8 

7  Worcester,  Mass.,  Imhoff  tank       6.00  .25         .10  21.0 

8  Cleveland,  Ohio,  Imhoff  tank       5.00  .25         .00  14.4 

9  Chicago,  111.,  Stock  Yards 

Imhoff  tank  8.50  .25       4.00  17.3         4.25 


Nin 
sludge 
nitri- 
fied 
mgs. 

8.65 

Per  cent 
N  in 
sludge 
nitri- 
fied 

32.5 

5.40 

43.9 

5.00 

32.4 

5.25 

28.7 

6.40 

38.0 

6.15 

25.7 

5.65 

26.9 

4.75 

32.9 

24.5 


TABLE  IV 

Availability  of  Nitrogen  in  Sludges  in  Oakley  Sand  (Cal.) 

Nitrate  N       Mgs.  nitrate 

found  nitrogen  Total 

after  in  N  in 

incubation  f A N  sludge 

No.  Description  mgs.  Soil       Sludge  mgs. 

1  Orange  City  Imhoff  tank  9.00         .30         .12  26.60 

2  Fullerton  Imhoff  tank   6.00         .30         .45  12.30 

3  Anaheim  Municipal  tank  7.00         .30       1.15  15.40 

4  Lindsay  septic  tank  4.50         .30         .90  18.30 

5  Pasadena  Imhoff  tank  6.40         .30       1.35  16.80 

6  Orange  City  Imhoff  tank  6.00         .30         .60  23.80 

7  Worcester,  Mass.,  Imhoff  tank       3.00         .30         .10  21.00 

8  Cleveland,  Ohio,  Imhoff  tank       1.50         .30         .00  14.40 

9  Chicago,  111.,  Stock  Yards 

Imhoff  tank,  5/14  6.00         .30       4.00  17.30       1.70 


Nin 
sludge 
nitri- 
fied 
mgs. 

8.60 

Per  cent 
N  in 
sludge 
nitri- 
fied 
32.30 

5.35 

43.50 

5.55 

36.00 

3.30 

18.00 

4.75 

28.20 

5.10 

21.40 

2.60 

12.40 

1.20 

8.33 

9.80 


BULLETIN  251]    UTILIZATION  OF  NITROGEN  AND  ORGANIC  MATTER  291 

Several  very  interesting  facts  appear  in  the  foregoing  tables.  Not 
only  do  the  different  sludges  behave  differently  in  any  one  soil,  but 
the  different  soils  manifest  markedly  different  capacities  for  rendering 
the  nitrogen  of  sludge  in  the  general  sense  "available."  Thus  we 
find  first,  that  in  the  Anaheim  soil  the  amount  of  organic  nitrogen 
in  the  sludge  added  which  is  nitrified,  varies  from  10.1  per  cent  in  the 
case  of  the  Chicago  sludge  to  44.1  per  cent  in  the  case  of  the  Cleveland 
sludge.  In  the  Davis  soil  the  corresponding  figures  are  24.5  per  cent 
in  the  case  of  the  Chicago  sludge,  and  43.9  per  cent  in  the  case  of  the 
Fullerton  (California),  sludge.  In  the  Oakley  sand  the  variation  is 
greatest  of  all,  and  namely  from  8.30  percent,  in  the  case  of  the  Cleve- 
land sludge  to  43.50  per  cent  in  the  case  of  the  Fullerton  sludge.  In 
the  second  place,  it  appears  that  the  Davis  soil  is  best  suited  to  sludge, 
using  that  term  in  its  general  sense  again,  of  the  three  soils  above 
studied.  In  no  case  does  it  convert  less  than  24.5  per  cent  of  the  nitro- 
gen in  the  sludge  into  nitrate,  and  the  total  range  in  degree  of  nitrifi- 
ability  of  the  organic  nitrogen  in  all  the  sludges  tested  with  the  Davis 
soil  is  less  than  20  per  cent.  The  corresponding  range  for  the  Anaheim 
soil  is  34  per  cent  and  that  for  the  Oakley  soil  a  little  over  35  per  cent. 
On  the  other  hand,  the  three  soils  can  scarcely  be  said  to  differ  in 
maximum  power  to  render  organic  sludge  nitrogen  into  nitrate  since 
that  is  accomplished  to  the  extent  of  about  44  per  cent  in  every  one 
of  them  and  not  beyond.  Some  other  noteworthy  differences  may  be 
called  to  the  reader 's  attention,  however.  While  the  Davis  soil  appears 
to  be  best  suited,  from  the  point  of  view  here  considered,  for  sludges 
in  general,  the  Anaheim  soil  transforms  40  per  cent  or  more  of  the 
sludge  nitrogen  into  nitrates  in  the  case  of  three  different  sludges, 
whereas  the  Davis  soil  does  so  in  but  one  case  as  does  also  the  Oakley 
soil.  In  general,  it  must  be  added  that  for  a  "low  grade"  material 
sludge  nitrogen  shows  a  surprisingly  high  availability  even  as  com- 
pared with  the  best  nitrogenous  materials  as  will  be  further  shown 
below. 

COMPAEISON    OF    THE    AVAILABILITY    OF    NITROGEN    IN    SLUDGES 
WITH  THAT  OF  COMMON  OEGANIC  NITROGENOUS  FERTILIZERS 

In  view  of  the  foregoing  results  of  experiments  it  appears  logical 
to  inquire  next  how  the  nitrogen  of  the  sludges  above  discussed  com- 
pares in  availability  with  that  in  some  of  the  more  important  com- 
mercial nitrogenous  fertilizers  of  an  organic  nature.  For  that  pur- 
pose we  have  arranged  in  Table  V  data  showing  the  availabilities  of  the 
nitrogen  in  the  various  sludges  used  in  the  California  soils  of  these 
experiments. 


292  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

as  compared  with  those  of  the  nitrogen  in  dried  blood,  high-grade 

tankage,   low-grade  tankage,   fish   guano,   cottonseed   meal,  and   goat 
manure  in  the  same  soils.     Table  V  follows : 

TABLE  V 

Comparison  of  the  Availability  of  Nitrogen  in  Sludges  with  that  in 
Common  Commercial  Nitrogen  Carriers 

Davis  Soil             Oakley  Soil  Anaheim  Soil 

Per  cent  N           Per  cent   N  Per  cent  N 

No.                   Description                                                      available                available  available 

1  Orange  City  Imhoff  tank  32.50                 32.30  27.20 

2  Fullerton  Imhoff  tank  43.90                 43.50  40.60 

3  Anaheim  Municipal  tank  32.40                 36.00  40.20 

4  Lindsay  septic  tank  28.70                 18.00  18.80 

5  Pasadena  Imhoff  tank  38.00                 28.20  35.70 

6  Orange  City  Imhoff  tank  25.70                  21.40  15.70 

7  Worcester,  Mass.,  Imhoff  tank  26.90                  12.40  34.50 

8  Cleveland,  Ohio,  Imhoff  tank  32.90                   8.30  44.10 

9  Chicago,  111.,  Stock  Yards  Imhoff  tank       24.50                   9.80  10.10 

10  Dried  blood  12.79                      .00  4.05 

11  High-grade  tankage  16.21                      .00  3.95 

12  Low-grade  tankage  27.39                  22.70  43.89 

13  Fish  guano  15.11                  trace  4.65 

14  Cottonseed  meal   14.18                   2.00  21.45 

15  Goat  manure  4.89                    3.50  10.39 


It  is  nothing  short  of  striking  to  note  in  Table  V  the  great  super- 
iority of  the  sludge  nitrogen  to  that  of  the  other  nitrogenous  materials 
when  they  are  compared  on  the  basis  of  "availability,"  used  in  the 
sense  of  nitrifiability.  Moreover,  it  is  not  merely  the  low  nitrogen 
content  of  the  sludge  which  brings  out  the  marked  contrast  just  dis- 
cussed, since  the  absolute  amounts  of  nitrate  produced  from  sludge 
nitrogen,  are  often  50  per  cent  to  75  per  cent  as  high  as  those  produced 
from  similar  weights  of  dried  blood,  or  high-grade  tankage.  Studying 
more  in  detail  the  data  set  forth  in  Table  V  we  find  that  low-grade 
tankage  is  the  only  material  of  the  six  employed  besides  the  sludges 
that  belongs  in  the  same  class  with  the  last  named  materials  from  the 
point  of  view  of  nitrifiability.  Dried  blood  and  tankage  are  not 
nitrified  at  all  in  the  Oakley  soil  and  but  slightly  in  the  Anaheim  soil, 
and  the  fish  guano  behaves  very  much  like  the  other  two.  Indeed 
the  conclusion  seems  almost  irresistible  that  the  nitrogen  of  the  so- 
called  low-grade  materials  is  most  easily  rendered  available  of  any 
of  the  organic  nitrogenous  materials.  Briefly,  therefore,  sludge  nitro- 
gen  is  to  be  considered  of  greater  value,  if  nitrifiability  thereof  is  any 


BULLETIN  251]    UTILIZATION  OF  NITROGEN  AND  ORGANIC  MATTER  293 

guide  at  all,  than  any  of  the  other  materials  named  in  Table  V,  except 
low-grade  tankage  and  fully  as  valuable  as  the  latter.  This  is  true 
when  the  availability  of  the  nitrogen  as  measured  by  nitrification  in 
California  soils  is  used  as  a  criterion,  and  even  more  strikingly  so  when 
eastern  soils  are  used  as  pointed  out  above.  The  many  interesting- 
topics  of  discussion  which  arise  from  a  careful  consideration  of  Table  V 
are  of  far-reaching  importance  to  both  the  theory  and  practice  of 
nitrogen  fertilization,  but  the  space  of  this  paper  will  not  permit  of 
their  consideration  here.  This  may  be  added,  however,  that  it  is  not 
an  insignificant  fact  that  the  Davis  soil  throughout,  as  has  already 
been  remarked  above,  seems  to  be  the  one  of  the  three  tested  which 
comes  nearest  to  being  a  generally  favorable  medium  for  the  nitrifi- 
cation of  all  the  forms  of  nitrogen  but  still  not  the  best  for  some  forms 
of  nitrogen. 


HOW  SLUDGES  SHOULD  BE  USED,  ALONE,  AND  WITH  FERTILIZERS 

In  soils  which  are  rich  in  the  mineral  plant  foods  and  are  known 
to  be  lacking  only  in  organic  matter  and  nitrogen  (both  total  and 
available)  sludge  should  be  used  in  the  air-dry  and  ground  form  at 
the  rate  of  at  least  one  ton  to  the  acre.  This  should  be  applied  to  the 
land  prior  to  the  early  spring  plowing  in  the  case  of  orchards  and 
vineyards  and  prior  to  fall  plowing  in  the  case  of  grain  land.  It  can 
be  either  broadcasted  or  drilled  in.  Such  applications  are  particu- 
larly to  be  recommended  for  the  light  colored  and  compacted  soils  of 
our  hot  valleys,  the  lighter  soils  needing  them  the  most.  The  frequency 
of  application  can  not  be  recommended  in  general  since  ' '  circumstances 
will  alter  cases."  Individual  cases,  however,  can  be  prescribed  for, 
if  necessary,  by  the  Agricultural  Experiment  Station  on  an  examina- 
tion of  the  soil  in  question. 

In  soils  poor  in  phosphoric  acid,  as  well  as  in  total  and  available 
nitrogen,  the  following  sludge  mixture  may  be  employed  per  acre  : 

2000  lbs.  finely  ground  sludge. 
300  lbs.  superphosphate. 

In  soils  with  a  high  iron  content  600  to  800  pounds  of  Thomas 
Phosphate  powder  may  be  substituted  for  the  superphosphate.  If 
only  an  addition  of  phosphoric  acid  is  desired,  however,  and  availability 
is  not  a  consideration,  finely  ground  steamed  bone  meal  may  be  sub- 
stituted at  the  rate  of  1200  pounds  per  acre  for  the  sludge  and 
phosphate  mixture. 


294  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

To  soils  deficient  in  all  three  of  the  so-called  fertilizer  elements 
(which  are  not  very  common  in  California),  or  to  those  "humus  poor" 
soils  which  do  not  contain  enough  available  phosphoric  acid  and  potash, 
the  following  sludge  mixture  may  be  employed  per  acre : 

2000  lbs.  finely  ground  sludge. 
300  lbs.  superphosphate. 
200-300  lbs.  sulphate  of  potash. 

Modifications  in  this  formula  may  be  made  in  accordance  with 
specific  cases  like  those  mentioned  above. 

In  soils  not  notably  lacking  in  nitrogen,  but  nevertheless  deficient 
in  that  important  element  and  especially  in  its  available  form,  the 
sludge  application  employed  per  acre  may  be  reduced  to  1000  or 
1200  pounds. 


CONCLUDING  REMARKS 

The  large  losses  suffered  by  our  soils  through  the  removal  of  sludge 
to  the  sea  or  through  the  direct  diversion  of  sewage  into  the  ocean 
can  hardly  be  appreciated.  According  to  Eisner  and  Spillner  it  has 
been  estimated  that  the  nitrogen  alone  in  the  world's  sewage  which 
is  lost  to  our  soils  is  worth  $143,000,000  annually.  While  this  estimate 
may  be  an  exaggeration  it  certainly  offers  food  for  thought.  What 
is  worse  is  that  money  is  not  only  lost  by  disposing  of  both  sewage 
and  sludge  through  dumping  into  the  sea,  but  in  most  places  in  which 
sludge  is  made  by  expensive  sewage  treatment  very  large  sums  of 
money  are  expended  annually  for  the  removal  of  the  sludge  to  the 
sea.  For  example,  to  quote  again  the  authorities  just  named,  the 
city  of  London  spends  annually  $238,000  merely  for  the  removal  in 
tank  steamers  to  the  sea  of  the  sludge  produced,  and  the  city  of 
Leipzig  in  Germany  spends  $7100  per  annum  mainly  for  removing 
dried  sludge.  In  other  words,  we  have  throughout  the  world  enormous 
double  waste  in  taxing  town  dwellers  heavily  to  treat  sewage  and 
remove  the  sludge  on  the  one  hand  and  then  in  robbing  our  soils  of 
their  just  due  by  dumping  the  sludge  into  the  sea. 

It  is  hard  to  account  for  the  indifferent  attitude  of  municipal  spec- 
ialists and  of  farmers  to  the  subject  of  the  utilization  of  sludge.  It 
seems  to  be  difficult  now  even  to  give  away  the  material  in  question  and 
certain  municipalities  have  paid  for  the  removal  of  the  sludge  from 
their  septic  tanks.  What  is  even  worse,  much  of  the  material  is 
annually  being  dumped  into  the  sea.     We  have  not  yet  learned,  as 


BULLETIN  251]    UTILIZATION  OF  NITROGEN  AND  ORGANIC  MATTER  295 

have  the  Orientals,  through  the  vicissitudes  of  dire  necessity,  to  con- 
serve our  resources.  The  natural  fertility  of  our  soils  is  still  too  great, 
and  our  acreage  too  large,  to  have  instilled  into  us  the  principles  of 
curtailment  of  waste.  The  Chinese  and  Japanese,  as  King  has  so  clearly 
shown  in  his  delightful  "Farmers  of  Forty  Centuries,"  have  learned 
their  lesson  well  by  force  of  circumstances,  and  scarcely  allow  anything 
to  go  to  waste  which  will  help  to  maintain,  no  matter  in  how  small  a 
degree,  the  fertility  of  their  rapidly  shrinking  acres. 

It  is  sincerely  hoped  that  the  evidence  set  forth  above  will  form 
another  strong  argument  for  the  utilization  of  sludge  from  municipal 
wastes  and  thereby  serve  to  enhance  or  to  maintain  the  longevity  of 
our  soils  as  profitable  crop  producers. 

For  the  purpose  of  setting  forth  clearly  the  statistical  data  with 
reference  to  sewage  and  sludge  wastes  in  California,  a  special  table 
is  arranged  for  the  reader  as  follows : 

TABLE  VI 

Important  Statistics  on  Sewage  and  Sludge  Wastes  in  California 

Population  served  by  sewerage  systems,  public  and  private  1,663,300 

Population  served  by  septic  tank  or  other  sewage  treatment  320,000 

Population  whose  sewage  is  used  on  sewer  farms,  etc 195,400 

Population  whose  sewage  or  sludge  or  both  go  to  the  sea  1,467,900 

Estimated  yield  of  air  dry  sludge  from  latter  per  annum,  in  tons 12,054.9 

Value  of  such  yield  merely  on  basis  of  total  nitrogen  and  phosphoric 

acid  contained $108,494.00 

Population  whose  loss   of  sewage   could  be  prevented  by   sewerage 

systems  1,000,000 

Value  of  sludge  from  latter  per  annum $72,330.00 

Total  loss  of  fertility  to  soils  of  California  on  conservative  basis $180,824.00 


STATION    PUBLICATIONS    AVAILABLE    FOR    DISTRIBUTION 


REPORTS 

1897.      Resistant  Vines,  their  Selection,   Adaptation,   and   Grafting.      Appendix  to   Viticultural 

Report  for  1896. 
Report  of  the   Agricultural   Experiment   Station   for   1898-1901. 
Report  of  the  Agricultural   Experiment   Station   for    1901-03. 
Twenty-second  Report  of  the  Agricultural  Experiment  Station  for  1903-04. 
Report  of  the   College   of  Agriculture   and  the  Agricultural    Experiment    Station,    July, 

1913-June,    1914. 


1902. 
1903. 
1904. 
1914. 


No. 
168. 

169. 

170. 
174. 
177. 

178. 
182. 

183. 
184. 

185. 

195. 
197. 


198. 
203. 


207. 
208. 


Observations    on    Some    Vine    Diseases 

in    Sonoma   County. 
Tolerance  of  the  Sugar  Beet  for  Alkali. 
Studies   in  Grasshopper  Control. 
A  New  Wine-Cooling  Machine. 
A    New    Method    of    Making   Dry    Red 

Wine. 
Mosquito  Control. 
Analysis    of    Paris     Green     and    Lead 

Arsenate.     Proposed  Insecticide  Law. 
The  California  Tussock-Moth. 
Report    of    the     Plant     Pathologist    to 

July  1,   1906. 
Report  of   Progress   in    Cereal   Investi- 
gations. 
The  California  Grape  Root-worm. 
Grape  Culture  in  California  :  Improved 

Methods      of      Wine-making;      Yeast 

from  California  Grapes. 
The  Grape  Leaf-Hopper. 
Report    of    the    Plant     Pathologist     to 

July   1,    1909. 
The  Control  of  the  Argentine  Ant. 
The  Late  Blight  of  Celery. 


BULLETINS 

No. 
211. 


212. 
213. 
216. 


225. 
227. 
230. 
234. 
240. 
241. 
242. 
243. 

244. 
245. 
246. 

248. 

249. 

250. 


How  to   Increase   the   Yield    of    Wheat 

in  California. 
California  White  Wheats. 
The  Principles  of  Wine-making. 
A    Progress    Report    upon    Soil    and 

Climatic     Factors     Influencing     the 

Composition  of  Wheat. 
Tolerance  of  Eucalyptus  for   Alkali. 
Grape  Vinegar. 
Enological  Investigations. 
Red  Spiders  and  Mites  of  Citrus  Trees. 
Commercial  Fertilizers. 
Vine  Pruning  in  California.     Part  I. 
Humus  in   California   Soils. 
The  Intradermal  Test  for  Tuberculosis 

in  Cattle  and  Hogs. 
LTtilization  of  Waste  Oranges. 
Commercial  Fertilizers. 
Vine  Pruning  in  California.      Part    II. 
The   Economic   Value   of   Pacific   Coast 

Kelps. 
Stock  Poisoning  Plants  of  California. 
The  Loquat. 


No. 
65. 

68. 
69. 

70. 

76. 
79. 
80. 
82. 

83. 
84. 
87. 
88. 


100. 
101. 


102. 

106. 


107 


CIRCULARS 

No. 

The   California    Insecticide   Law.  108. 

The  Prevention  of  Hog  Cholera.  109. 

The  Extermination  of  Morning-Glory. 
Observations    on    the    Status    of    Corn 

Growing  in  California.  110. 

Hot  Room  Callusing.  111. 

List  of  Insecticide  Dealers 

Boys'   and   Girls'   Clubs.  113. 

The    Common     Ground     Squirrels     of  114. 

California.  115. 

Potato  Growing  Clubs.  116. 

Mushrooms   and  Toadstools.  117. 

Alfalfa.  , 

Advantages  to  the  Breeder  in   Testing  118. 

his  Pure-bred  Cows  for  the  Register  119. 

of  Merit.  120. 

Disinfection  on  the  Farm. 
Infectious    Abortion     and     Sterility    in  121. 

Cows. 
Pruning  Frosted  Citrus  Trees.  122. 

Codling    Moth    Control    in    the    Sacra- 
mento Valley.  123. 
The  Woolly  Aphis. 
Directions  for  using  Anti-Hog-Cholera                124. 

Perum.  125. 

Spraving  Walnut  Trees  for  Blight  and 

Aphis  Control. 


Grape  Juice. 

Communitv  or  Local  Extension  Work 
by  the  High  School  Agricultural  De- 
partment. 

Green  Manuring  in  California. 

The  Use  of  Lime  and  Gypsum  on  Cali- 
fornia  Soils. 

Correspondence  Courses  in  Agriculture. 

Increasing  the  Dutv  of  Water. 

Grafting  Vinifera  Vineyards. 

Silk  Worm  Experiments. 

The  Selection  and  Cost  of  a  Small 
Pumping   Plant. 

The  Count"?  Farm  Bureau. 

Winery   Directions. 

Potato  Growing  in  the  San  Joaquin 
and  Sacramento  Deltas  of  California. 

Some  Things  the  Prospective  Pettier 
Should   Know. 

The  Management  of  Strawberry  Soils 
in  Pajaro  Valley. 

Fundamental  Principles  of  Co-opera- 
tion in  Agriculture. 

Alfalfa  Silage  for  Fattening  Steers. 

Aphids  on   Grain   and  Cantaloupes. 


